[Native File System] Disable API for Android

Disables the API for Android because we do not support it yet on this
platform and our users may get confused when the feature fails to work
as intended.

Also changes the expiry of the about flag for native-file-system-api to
M84, in view of a second Origin Trial in M81.

Bug: 1026017
Fixed: 1026017
Change-Id: I319107cad605c5056ed7654f362ddb0dbbfc2461
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1925089
Reviewed-by: Marijn Kruisselbrink <[email protected]>
Reviewed-by: Stefan Zager <[email protected]>
Reviewed-by: Colin Blundell <[email protected]>
Commit-Queue: Olivier Yiptong <[email protected]>
Cr-Commit-Position: refs/heads/master@{#717136}
diff --git a/chrome/browser/about_flags.cc b/chrome/browser/about_flags.cc
index 75ad26e..061ea2c 100644
--- a/chrome/browser/about_flags.cc
+++ b/chrome/browser/about_flags.cc
@@ -4075,7 +4075,7 @@
      FEATURE_VALUE_TYPE(features::kBuiltInModuleKvStorage)},
 
     {"native-file-system-api", flag_descriptions::kNativeFileSystemAPIName,
-     flag_descriptions::kNativeFileSystemAPIDescription, kOsAll,
+     flag_descriptions::kNativeFileSystemAPIDescription, kOsDesktop,
      FEATURE_VALUE_TYPE(blink::features::kNativeFileSystemAPI)},
 
     {"file-handling-api", flag_descriptions::kFileHandlingAPIName,